Semiconductor device with metal spacers and method for fabricating the same

ABSTRACT

The present application discloses a semiconductor device including a substrate, an active area in the substrate, a first plug positioned above the active area, second plugs positioned above the active area, metal spacers positioned above the first plug and the plurality of second plugs, and air gaps respectively positioned between the plurality of metal spacers. The active area includes a narrow portion having a first width and two side portions having a second width, wherein the narrow portion is disposed between the two side portions, and the first width is less than the second width from a top view.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of U.S. Non-Provisional application Ser. No. 17/533,414 filed Nov. 23, 2021, which is a divisional application of U.S. Non-Provisional application Ser. No. 16/665,350 filed Oct. 28, 2019. Those are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to a method for fabricating a semiconductor device, and more particularly to a method for fabricating a semiconductor device with metal spacers.

DISCUSSION OF THE BACKGROUND

Semiconductor device have applications in many electronic devices, including cellular telephones and other communication devices, automotive electronics, and other technology platforms. With the increased demand for improved functionality and miniaturization in these devices, the dimensions of semiconductor devices are continuously being scaled down to meet the increasing demand of computing ability. However, a variety of issues arise during the scaling-down process and impact the final electrical characteristics, quality, and yield. Therefore, challenges remain in achieving improved quality, yield, and reliability.

This Discussion of the Background section is provided for background information only. The statements in this Discussion of the Background are not an admission that the subject matter disclosed in this section constitutes prior art to the present disclosure, and no part of this Discussion of the Background section may be used as an admission that any part of this application, including this Discussion of the Background section, constitutes prior art to the present disclosure.

SUMMARY

One aspect of the present disclosure provides a semiconductor device including a substrate, an active area in the substrate, a first plug positioned above the active area, second plugs positioned above the active area, metal spacers positioned above the first plug and the plurality of second plugs, and air gaps respectively positioned between the plurality of metal spacers. The active area comprises a narrow portion having a first width and two side portions having a second width, wherein the narrow portion is disposed between the two side portions, and the first width is less than the second width from a top view.

Another aspect of the present disclosure provides a method for fabricating a semiconductor device. The method includes: providing a substrate; forming an active area in the substrate; forming a first plug above the active area; forming a plurality of second plugs above active area; forming a plurality of metal spacers above the first plug and the plurality of second plugs; and forming a plurality of air gaps positioned between the plurality of metal spacers. The active area comprises a narrow portion having a first width and two side portions having a second width, wherein the narrow portion is disposed between the two side portions, and the first width is less than the second width from a top view.

Due to the design of the semiconductor device of the present disclosure, the seams and voids may be reduced when filled high aspect ratio electroplated metal structure of the semiconductor device. Therefore, the electrical transport performance of the semiconductor device may be improved.

The foregoing has outlined rather broadly the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter, and form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 illustrates, in a schematic cross-sectional view diagram, a semiconductor device in accordance with one embodiment of the present disclosure.

FIG. 2 illustrates, in a schematic cross-sectional view diagram, a semiconductor device in accordance with another embodiment of the present disclosure.

FIG. 3 illustrates, in a flowchart diagram form, a method for fabricating a semiconductor device in accordance with one embodiment of the present disclosure.

FIG. 4 illustrate, in schematic cross-sectional diagrams, part of a flow of fabricating a semiconductor device in accordance with one embodiment of the present disclosure.

FIG. 5 illustrates, in a schematic top-view diagram, the semiconductor device in accordance with FIG. 4 .

FIGS. 6 to 11 illustrate, in schematic cross-sectional diagrams, part of the flow of fabricating the semiconductor device in accordance with one embodiment of the present disclosure.

FIG. 12 illustrates, in a schematic top-view diagram, the semiconductor device in accordance with FIG. 11 .

FIGS. 13 to 14 illustrate, in schematic cross-sectional diagrams, part of the flow of fabricating the semiconductor device in accordance with one embodiment of the present disclosure.

FIGS. 15 to 19 illustrate, in schematic cross-sectional diagrams, part of the flow of fabricating the semiconductor device in accordance with one embodiment of the present disclosure.

FIGS. 20 to 24 illustrate, in schematic cross-sectional diagrams, some semiconductor devices in accordance with another embodiment of the present disclosure.

FIG. 25 illustrates, in a schematic cross-sectional view diagram, a semiconductor device in accordance with one embodiment of the present disclosure.

FIG. 26 illustrates, in a schematic cross-sectional view diagram, a semiconductor device in accordance with another embodiment of the present disclosure.

FIG. 27 illustrates, in a schematic top view diagram, a semiconductor device in accordance with some embodiments of the present disclosure.

FIG. 28 illustrates, in a schematic cross-section view diagram, a semiconductor device in accordance with various embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

It will be understood that when an element or layer is referred to as being “connected to,” or “coupled to” another element or layer, it can be directly connected to or coupled to another element or layer or intervening elements or layers may be present.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. Unless indicated otherwise, these terms are only used to distinguish one element from another element. Thus, for example, a first element, a first component or a first section discussed below could be termed a second element, a second component or a second section without departing from the teachings of the present disclosure.

Unless the context indicates otherwise, terms such as “same,” “equal,” “planar,” or “coplanar,” as used herein when referring to orientation, layout, location, shapes, sizes, amounts, or other measures do not necessarily mean an exactly identical orientation, layout, location, shape, size, amount, or other measure, but are intended to encompass nearly identical orientation, layout, location, shapes, sizes, amounts, or other measures within acceptable variations that may occur, for example, due to manufacturing processes. The term “substantially” may be used herein to reflect this meaning. For example, items described as “substantially the same,” “substantially equal,” or “substantially planar,” may be exactly the same, equal, or planar, or may be the same, equal, or planar within acceptable variations that may occur, for example, due to manufacturing processes.

In the present disclosure, a semiconductor device generally means a device which can function by utilizing semiconductor characteristics, and an electro-optic device, a light-emitting display device, a semiconductor circuit, and an electronic device are all included in the category of the semiconductor device.

It should be noted that, in the description of the present disclosure, above (or up) corresponds to the direction of the arrow of the direction Z, and below (or down) corresponds to the opposite direction of the arrow of the direction Z.

FIG. 1 illustrates, in a schematic cross-sectional view diagram, a semiconductor device in accordance with one embodiment of the present disclosure.

With reference to FIG. 1 , in the embodiment depicted, a semiconductor device 100A may include a substrate 101, a plurality of isolation structures 103, an active area 105, a plurality of doped regions, a poly line 200, a plurality of contacts 403, a plurality of plugs, a plurality of metal spacers, a plurality of air gaps 600, and a plurality of insulating films.

With reference to FIG. 1 , in the embodiment depicted, the substrate 101 may be formed of, for example, silicon, doped silicon, silicon germanium, silicon on insulator, silicon on sapphire, silicon germanium on insulator, silicon carbide, germanium, gallium arsenide, gallium phosphide, gallium arsenide phosphide, indium phosphide, or indium gallium phosphide. When the substrate 101 is formed of silicon-on-insulator, the substrate 101 may include a top semiconductor layer and a bottom semiconductor layer formed of silicon, and a buried insulating layer which may separate the top semiconductor layer and the bottom semiconductor layer. The buried insulating layer may include, for example, a crystalline or non-crystalline oxide, nitride or any combination thereof.

With reference to FIG. 1 , in the embodiment depicted, the plurality of isolation structures 103 may be disposed in the substrate 101. The plurality of isolation structures 103 may be formed of, for example, an insulating material such as silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, or fluoride-doped silicate. The plurality of isolation structures 103 may define the active area 105 of the substrate 101.

It should be noted that, in the present disclosure, silicon oxynitride refers to a substance which contains silicon, nitrogen, and oxygen and in which a proportion of oxygen is greater than that of nitrogen. Silicon nitride oxide refers to a substance which contains silicon, oxygen, and nitrogen and in which a proportion of nitrogen is greater than that of oxygen.

With reference to FIG. 1 , in the embodiment depicted, the plurality of doped regions include a first doped regions 107 and a plurality of second doped regions 301. The first doped regions 107 may be disposed in an upper portion of the active area 105 of the substrate 101. The first doped region 107 may be doped by with a dopant such as phosphorus, arsenic, antimony, boron, aluminum or gallium.

With reference to FIG. 1 , in the embodiment depicted, the poly line 200 may be disposed above the first region 107. The poly line 200 may include a gate oxide 203, a poly gate 207, and a plurality of spacers 211. The gate oxide 203 may be disposed on a top of the substrate 101 and under the poly gate 207. The poly gate 207 may be disposed above the substrate 101 and on a top of the gate oxide 203. Both the gate oxide 203 and the poly gate 207 are disposed between the two spacers 211. The plurality of spacers 211 may be disposed on a top of the substrate 101 and adjacent to the sidewalls of the gate oxide 203 and the poly gate 207. The gate oxide 203 may be formed of, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, or the like. The poly gate 207 may be formed of, for example, polysilicon, or the like. The plurality of spacers 211 may be formed of, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, or the like.

With reference to FIG. 1 , in the embodiment depicted, the plurality of second doped regions 301 may be disposed in the first doped region 107 and respectively disposed between the plurality of isolation structures 103. The plurality of second doped regions 301 may doped with a dopant such as phosphorus, arsenic, antimony, boron, aluminum or gallium.

With reference to FIG. 1 , in the embodiment depicted, the plurality of contacts 403 may be disposed respectively on a top of the poly gate 207 and the plurality of second doped regions 301. The plurality of contacts 403 may be formed, for example, cobalt, titanium, tungsten-silicide, or the like.

With reference to FIG. 1 , in the embodiment depicted, the plurality of insulating films include a first insulating film 901, a second insulting film 903, a third insulating film 905, and a sealing film 907. The first insulating film 901 may be disposed above the substrate 101 and cover the poly line 200 and the plurality of contacts 403. The second insulating film 903 may be disposed on the first insulating film 901. The third insulating film 905 may be disposed on the second insulating film 903. The sealing film 907 may be disposed on the third insulating film 905. The first insulating film 901 and the second insulating film 903 may be formed of, for example, silicon nitride, silicon oxide, silicon oxynitride, undoped silica glass, borosilica glass, phosphosilica glass, borophosphosilica glass, or a combination thereof, but is not limited thereto. The third insulating film 905 and the sealing film 907 may be formed of a same material as the first insulating film 901, but is not limited thereto. The plurality of plugs may be disposed above the plurality of contacts 403. The plurality of plugs may be disposed passed through the first insulating film 901 and the second insulating film 903. The plurality of plugs may be formed, for example, aluminum, copper, tungsten, cobalt, or other suitable metal or metal alloy or the like. Specifically, the plurality of plugs may include a first plug 501 and two second plugs 503. The first plug 501 may be disposed on the poly line 200. The two second plugs may be respectively correspondingly disposed above the plurality of second doped regions 301.

With reference to FIG. 1 , in the embodiment depicted, the plurality of metal spacers may be disposed above the substrate 101. The plurality of metal spacers may be formed, for example, aluminum, copper, tungsten, cobalt, or other suitable metal or metal alloy or the like. The plurality of metal spacers may include a first set of metal spacers, a second set of metal spacers, a third set of metal spacers, and a fourth set of metal spacers. The second set of metal spacers may be disposed between the first set of metal spacers and the third set of metal spacers. The third set of metal spacers may be disposed between the second set of metal spacers and the fourth set of metal spacers. The first set of metal spacers may be disposed on one of the two of second plugs 503. The second set of metal spacers may be disposed on first plug 501. The third set of metal spacers may be disposed on another one of the two second plugs 503. The fourth set of metal spacers may be disposed on a top surface of the second insulating film 903. In other words, the first set of metal spacers, the second set of metal spacers, and the third set of metal spacers may be electrically connected to the plurality of plugs. The fourth set of metal spacers may be dummy; that is to say, the fourth set of metal spacers may not electrically connect or couple to any conductive element.

With reference to FIG. 1 , in the embodiment depicted, the first set of metal spacers includes a first metal spacer 601 and a second metal spacer 603. The first metal spacer 601 and the second metal spacer 603 may be disposed on the one of the two of second plugs 503 and in the third insulating film 905. The first metal spacer 601 may have two sidewalls. One of the two sidewalls of the first metal spacer 601 may be attached to the third insulating film 905. The second metal spacer 603 may be attached to another one of the two sidewalls of the first metal spacer 601. A combined bottom width of the first metal spacer 601 and the second metal spacer 603 may be equal to or greater than a top width the one of the two of second plugs 503.

With reference to FIG. 1 , in the embodiment depicted, the second set of metal spacers includes a third metal spacer 605 and a fourth metal spacer 607. The third metal spacer 605 and the fourth metal spacer 607 may be disposed on the first plug 501 and in the third insulating film 905. The fourth metal spacer 607 may have two sidewalls. One of the two sidewalls of the fourth metal spacer 607 may be attached to the third insulating film 905. The third metal spacer 605 may be attached to another one of the two sidewalls of the fourth metal spacer 607. The second metal spacer 603 and the third metal spacer 605 may be opposite to each other. A combined bottom width of the third metal spacer 605 and the fourth metal spacer 607 may be equal to or greater than a top width of the first plug 501. In addition, the third metal spacer 605 and the second metal spacer 603 may have mirror symmetry in a cross-sectional view. The fourth metal spacer 607 and the first metal spacer 601 may have mirror symmetry in a cross-sectional view.

With reference to FIG. 1 , in the embodiment depicted, the third set of metal spacers includes a fifth metal spacer 609 and a sixth metal spacer 611. The fifth metal spacer 609 and the sixth metal spacer 611 may be disposed on the other one of the two of second plugs 503 and in the third insulating film 905. The fifth metal spacer 609 may have two sidewalls. One of the two sidewalls of the fifth metal spacer 609 may be attached to the third insulating film 905. The sixth metal spacer 611 may be attached to another one of the two sidewalls of the fifth metal spacer 609. A combined bottom width of the fifth metal spacer 609 and the sixth metal spacer 611 may be equal to or greater than a top width of the other one of the two of second plugs 503. The fifth metal spacer 609 may be opposite to the fourth metal spacer 607 with the third insulating film 905 interposed therebetween. In addition, the fifth metal spacer 609 may have a same profile/shape as the first metal spacer 601 in a cross-sectional diagram. The sixth metal spacer 611 may have a same profile/shape as the second metal spacer 603 in a cross-sectional diagram.

With reference to FIG. 1 , in the embodiment depicted, the fourth set of metal spacers includes a seventh metal spacer 613 and an eighth metal spacer 615. The seventh metal spacer 613 and the eighth metal spacer 615 may be disposed on the top surface of the second insulating film 903 and in the third insulating film 905. In other words, the seventh metal spacer 613 and the eighth metal spacer 615 may be dummy; that is to say, the seventh metal spacer 613 and the eighth metal spacer 615 may not electrically connect or couple to any conductive element. The seventh metal spacer 613 may be opposite to the sixth metal spacer 611. In addition, the seventh metal spacer 613 may have a same profile/shape as the third metal spacer 605 in a cross-sectional diagram. The eighth metal spacer 615 may have a same profile/shape as the fourth metal spacer 607 in a cross-sectional diagram. Furthermore, the seventh metal spacer 613 and the sixth metal spacer 611 may have mirror symmetry in a cross-sectional view. The eighth metal spacer 615 and the fifth metal spacer 609 may have mirror symmetry in a cross-sectional view.

With reference to FIG. 1 , in the embodiment depicted, the plurality of air gaps 600 may be disposed above the substrate 101 and in the third insulating film 905. The plurality of air gaps 600 may be respectively corresponding disposed between the first set of metal spacers and the second set of metal spacers, and between the third set of metal spacers and the fourth set of metal spacers. Specifically, the plurality of air gaps 600 may be respectively correspondingly disposed between the second metal spacer 603 and the third metal spacer 605, and between the sixth metal spacer 611 and the seventh metal spacer 613. One of the plurality of air gaps 600 may respectively be spaces surrounded by the sealing film 907, the second metal spacer 603, the third metal spacer 605, and the second insulating film 903. The other one of the plurality of air gaps 600 may be respectively surrounded by the sealing film 907, the sixth metal spacer 611, the seventh metal spacer 613, and the second insulating film 903.

FIG. 2 illustrates, in a schematic cross-sectional view diagram, a semiconductor device 100B in accordance with another embodiment of the present disclosure.

With reference to FIG. 2 , the first metal spacer 601 may further include a first protruding portion 617. The first protruding portion 617 may be extended form a lower portion of the first metal spacer 601, along a first direction Y, and toward the fourth metal spacer 607. In other words, the first metal spacer 601 may have an L-shaped profile in a cross-sectional view. The first protruding portion 617 may be disposed on the one of the two second plugs 503. A width of the first protruding portion 617 may be equal to or greater than the width of the top surface of the one of the two second plugs 503. The second metal spacer 603 may be disposed on the first protruding portion 617.

With reference to FIG. 2 , the fourth metal spacer 607 may further include a second protruding portion 619. The second protruding portion 619 may be extended form a lower portion of the fourth metal spacer 607, along the first direction Y, and toward the first metal spacer 601. In other words, the fourth metal spacer 607 and the first metal space 601 may have a mirrored L-shaped profile in a cross-sectional view. The second protruding portion 619 may be disposed on the first plug 501. A width of the second protruding portion 619 may be equal to or greater than the width of the top surface of the first plugs 501. The third metal spacer 605 may be disposed on the second protruding portion 619.

With reference to FIG. 2 , the fifth metal spacer 609 may further include a third protruding portion 621. The third protruding portion 621 may be extended form a lower portion of the fifth metal spacer 609, along the first direction Y, and toward the eighth metal spacer 615. In other words, the fifth metal spacer 609 may have an L-shaped profile in a cross-sectional view. The third protruding portion 621 may be disposed on the other one of the two second plugs 503. A width of the third protruding portion 621 may be equal to or greater than the width of the top surface of the other one of the two second plugs 503. The sixth metal spacer 611 may be disposed on the third protruding portion 621.

With reference to FIG. 2 , the eighth metal spacer 615 may further include a fourth protruding portion 623. The fourth protruding portion 623 may be extended form a lower portion of the eighth metal spacer 615, along the first direction Y, and toward the fifth metal spacer 609. In other words, the eighth metal spacer 615 and the fifth metal spacer 609 may have a mirrored L-shaped profile in a cross-sectional view. The fourth protruding portion 623 may be disposed on the second insulating film 903. The seventh metal spacer 613 may be disposed on the fourth protruding portion 623.

With reference to FIG. 2 , one of the plurality of air gaps 600 may be respectively spaces surrounded by the sealing film 907, the second metal spacer 603, the third metal spacer 605, the first protruding portion 617, the second protruding portion 619, and the second insulating film 903. The other one of the plurality of air gaps 600 may be respectively surrounded by the sealing film 907, the sixth metal spacer 611, the seventh metal spacer 613, the third protruding portion 621, the fourth protruding portion 623, and the second insulating film 903.

FIG. 3 illustrates, in a flowchart diagram form, a method 10 for fabricating a semiconductor device in accordance with one embodiment of the present disclosure. FIGS. 4 and 5 illustrate part of the flow of fabricating a semiconductor device in accordance with one embodiment of the present disclosure. FIG. 5 illustrates, in a schematic top-view diagram, the semiconductor device in accordance with FIG. 4 .

With reference to FIG. 3 at step S11, the substrate 101 may be provided. With reference to FIG. 3 , at step S13, the plurality of isolation structures 103 may be formed in the substrate 101. The plurality of isolation structures 103 may define the active area 105 of the substrate 101. A photolithography process may be used to pattern the substrate 101 to define positions of the plurality of isolation structures 103, then an etch process, such as an anisotropic dry etch process, may be performed to form the plurality of isolation structures openings in the substrate 101. After the etch process, an oxidation process may be performed such as thermal oxidation, chemical vapor deposition to form the plurality of isolation structures 103.

With reference to FIG. 3 , at step S15, the first doped region 107 may be formed in the substrate 101. The first doped region 107 may be doped with a dopant such as phosphorus, arsenic, antimony, boron, aluminum or gallium by an implantation process.

With reference to FIGS. 3 , and FIGS. 4 and 5 , at step S17, the poly line 200 may be formed above the substrate 101. With reference to FIG. 4 , an oxidation process may be performed such as thermal oxidation, chemical vapor deposition to form a gate oxide layer. A first photolithography process may be used to pattern the gate oxide layer to define positions of a gate oxide 203, then an etch process, such as an anisotropic dry etch process, may be performed to form the gate oxide 203 on the substrate 101. After gate oxide 203 may be formed, a poly gate layer may be formed by used such as chemical vapor deposition, physical vapor deposition, or sputtering. A second photolithography process may be used to pattern the poly gate layer to define positions of a poly gate 207, then an etch process, such as an anisotropic dry etch process, may be performed to form the poly gate 207 on the gate oxide 203. Then, the spacer layer may be formed by used such as thermal oxidation, chemical vapor deposition or the like. With reference to FIG. 4 , then an etch process, such as an anisotropic dry etch process, may be performed to form the plurality of spacers 211 which adjacent to the sidewalls of the poly oxide 203 and the poly gate 207.

FIGS. 6 to 12 illustrate part of the flow of fabricating a semiconductor device in accordance with one embodiment of the present disclosure. FIG. 12 illustrates, in a schematic top-view diagram, the semiconductor device in accordance with FIG. 11 and FIGS. 13 to 19 illustrate part of the flow of fabricating a semiconductor device in accordance with one embodiment of the present disclosure.

With reference to FIGS. 3 and 6 , at step S19, the plurality of second doped regions 301 may be formed in the first doped region 107 and respectively formed between the plurality of isolation structures 103. The plurality of second doped regions 301 may be doped with a dopant such as phosphorus, arsenic, antimony, boron, aluminum or gallium by an implantation process

With reference to FIGS. 3, 7, and 8 , at step S21, the plurality of contacts 403 may be formed above the substrate 101. The plurality of contacts 403 may be formed respectively on tops of the poly gate 207 and the plurality of second doped regions 301. With reference to FIG. 7 , a contact layer 401 may be formed of, for example, cobalt, titanium or other suitable metal or metal alloy, by deposition process such as chemical vapor deposition, physical vapor deposition, sputtering, or the like. With reference to FIG. 8 , an etch process, such as an anisotropic dry etch process, may be performed to form the plurality of contacts 403.

With reference to FIGS. 3, 9 to 12 , at step S23, the plurality of plugs may be formed above the substrate 101. The plurality of plugs may include a first plug 501 and two second plugs 503. With reference FIG. 9 , a first insulating film 901 may be formed by deposition process such as chemical vapor deposition, physical vapor deposition, sputtering, or the like. With reference FIG. 10 , the second insulating film 903 may be formed on the first insulating film 901 by deposition process same as formed the first insulating film 901. With reference FIG. 11 , a photolithography process may be used to pattern the second insulating film 903 to define positions of the plurality of plugs. An etch process, such as an anisotropic dry etch process, may be performed after the photolithography process to form the plurality of plugs opening passed through the second insulating film 903 and the first insulating film 901. After the etch process, a conductive material, for example, aluminum, copper, tungsten, cobalt, or other suitable metal or metal alloy is filled, by a metallization process such as chemical vapor deposition, physical vapor deposition, sputtering, or the like, in the plurality of plugs opening. The plurality of plugs may be formed after a planarization process, such as chemical mechanical polishing, may be performed after the metallization process to remove excess filling material and provide a substantially flat surface for subsequent processing steps. The first plug 501 may be formed above the poly line 200 and the two second plugs 503 may be respectively correspondingly formed above the plurality of second doped regions 301.

With reference to FIGS. 3, 13 to 18 , at step S25, a plurality of metal spacers may be formed above the substrate 101. With reference FIG. 13 , a third insulating film 905 may be formed on the second insulating film 903 by deposition process same as formed the first insulating film 901. With reference FIG. 14 , a photolithography process may be used to pattern the third insulating film 905 to define positions of a plurality of trenches 909. An etch process, such as an anisotropic dry etch process, may be performed after the photolithography process to form the plurality of trenches 909 passed through the third insulating film 905. Top surfaces of the plurality of plugs may be exposed through the plurality of trenches 909. With reference FIG. 15 , after the etch process, a conductive material, for example, aluminum, copper, tungsten, cobalt, or other suitable metal or metal alloy is deposited, by a deposition process such as chemical vapor deposition, physical vapor deposition, sputtering, or the like, in the plurality of trenches 909 to form a first metal spacer layer 801. The first metal spacer layer 801 cover a top surface and sidewalls of the third insulating film 905, and top surfaces of the plurality of plugs.

With reference FIG. 16 , an etch process, such as an anisotropic dry etch process, may be performed to respectively correspondingly form a first metal spacer 601, a fourth metal spacer 607, a fifth metal spacer 609, and an eighth metal spacer 615 attached to sidewalls of the plurality of trenches 909. The first metal spacer 601 may be disposed on one of the two second plugs 503 and electrically connected thereto. A combined bottom width of the first metal spacer 601 may be equal to or less than a top width of the one of the two second plugs 503. The fourth metal spacer 607 may be disposed on the first plug 501 and electrically connected thereto. A combined bottom width of the fourth metal spacer 607 may be equal to or less than a top width of the first plug 501. The fifth metal spacer 609 may be disposed on another one of the two second plugs 503 and electrically connected thereto. A combined bottom width of the fifth metal spacer 609 may be equal to or less than a top width of the other one of the two second plugs 503. The eighth metal spacer 615 may be disposed on the second insulating film 903. A planarization process, such as chemical mechanical polishing, may be performed after the etch process to remove residue material and provide a substantially flat surface for subsequent processing steps.

With reference to FIG. 17 , a second metal spacer layer 803 may be formed over the third insulating film 905. The second metal spacer layer 803 may be formed of a same conductive material as the first metal spacer layer 801, but is not limited thereto. The second metal spacer layer 803 may be deposited, by a deposition process such as chemical vapor deposition, physical vapor deposition, sputtering, or the like. The second metal spacer layer 803 cover the top surface of the third insulating film 905, a sidewall of first metal spacer 601, a sidewall of the fourth metal spacer 607, a sidewall of the fifth metal spacer 609, a sidewall of the eighth metal spacer 615, and bottoms of the plurality of trenches 909. The top surfaces of the first plug 501 and the two second plugs 503 may be covered by the second metal spacer layer 803.

With reference to FIG. 18 , an etch process, such as an anisotropic dry etch process, may be performed to respectively correspondingly form a second metal spacer 603, a third metal spacer 605, a sixth metal spacer 611, and a seventh metal spacer 613 respectively correspondingly attached to the sidewalls of the first metal spacer 601, the fourth metal spacer 607, the sixth metal spacer 611, and the seventh metal spacer 613. A planarization process, such as chemical mechanical polishing, may be performed after the etch process to provide a substantially flat surface for subsequent processing steps.

With reference back to FIGS. 1, 3 and 19 , at step S27, a plurality of air gaps 600 may be formed above the substrate 101. The sealing film 907 may be formed on the third insulating film 905 by deposition process same as formed the first insulating film 901. Then the remained spaces of the plurality of trenches 909 may be concurrently turned in to the plurality of air gaps 600 after the formation of the sealing film 907. It should be noted that the term “seal” can mean either sealing the plurality of air gaps 600 without filling the plurality of air gaps 600 with any of the material formed of the sealing film 907, or sealing the plurality of air gaps 600 while partially filling the plurality of air gaps 600 with some of the material formed of the sealing film 907. A thickness of the sealing film 907 may be about 1000 Angstroms to about 5000 Angstroms. However, the thickness of the sealing film 907 may be set to an arbitrary range depending on the circumstances.

FIGS. 20 to 24 illustrate, in schematic cross-sectional diagrams, part of a flow of fabricating a semiconductor device in accordance with another embodiment of the present disclosure.

With reference to FIG. 20 , the first metal spacer layer 801 may be formed by a deposition process such as chemical vapor deposition, physical vapor deposition, sputtering, or the like over the third insulating film 905 and in the plurality of trenches 909. The first metal spacer layer 801 may cover the top surface of the third insulating film 905, the bottoms and the sidewalls of the plurality of trenches 909.

With reference to FIG. 21 , the second metal spacer layer 803 may be formed by a deposition process such as chemical vapor deposition, physical vapor deposition, sputtering, or the like over the first metal spacer layer 801. The second metal spacer layer 803 may be a conductive material having etching selectivity to the first metal spacer layer 801. With reference to FIG. 22 , an etch process, such as an anisotropic dry etch process, may be performed to remove portions of the second metal spacer layer 803 and concurrently form the second metal spacer 603, the third metal spacer 605, the sixth metal spacer 611, and the seventh metal spacer 613 disposed on the first metal spacer layer 801. A planarization process, such as chemical mechanical polishing, may be performed to provide a substantially flat surface for subsequent processing steps.

With reference FIG. 23 , an etch process, such as an anisotropic dry etch process, may be performed to form the first metal spacer 601, the fourth metal spacer 607, the fifth metal spacer 609, and the eighth metal spacer 615. It should be noted that, during the etching process, the second metal spacer 603, the third metal spacer 605, the sixth metal spacer 611, and the seventh metal spacer 613 may be respectively correspondingly serve as masks for the first metal spacer 601, the fourth metal spacer 607, the fifth metal spacer 609, and the eighth metal spacer 615. As a result of that, a first protruding portion 617 of the first metal spacer 601, a second protruding portion 619 of the fourth metal spacer 607, a third protruding portion 621 of the fifth metal spacer 609, and a fourth protruding portion 623 of the eighth metal spacer 615 may respectively correspondingly formed below the second metal spacer 603, the third metal spacer 605, the sixth metal spacer 611, and the seventh metal spacer 613. A planarization process may be performed to provide a substantially flat surface for subsequent processing steps.

With reference to FIGS. 2 and 24 , the plurality of air gaps 600 may be formed above the substrate 101. The sealing film 907 may be formed on the third insulating film 905 by deposition process same as formed the first insulating film 901. Next, the plurality of air gaps 600 may be concurrently formed after the formation of the sealing film 907.

FIG. 25 illustrates, in a schematic cross-sectional view diagram, a semiconductor device 100C in accordance with one embodiment of the present disclosure. In the embodiment depicted, the semiconductor device 100C may include a substrate 101, a plurality of isolation structures 103, an active area 105, a plurality of doped regions 107 and 301, a poly line 200, a plurality of contacts 403, a plurality of plugs 501 and 503, a plurality of metal spacers, a plurality of air gaps 700A and 700B, and a plurality of insulating films 901, 903, 905 and 907.

In some embodiments, the plurality of metal spacers comprise a first metal spacer 701 positioned on the plug 503 and a second metal spacer 703 positioned between the first metal spacer 701 and the air gap 700A over the plug 503. In some embodiments, a combined bottom width of the first metal spacer 701, the second metal spacer 703 and the air gap 700A is equal to or greater than a top width of the plug 503.

In some embodiments, the plurality of metal spacers comprise a first metal spacer 705 positioned on the plug 501 and a second metal spacer 707 positioned between the first metal spacer 705 and the air gap 700B over the plug 501. In some embodiments, a combined bottom width of the first metal spacer 705, the second metal spacer 707 and the air gap 700B is equal to or greater than a top width of the plug 501.

FIG. 26 illustrates, in a schematic cross-sectional view diagram, a semiconductor device 100D in accordance with another embodiment of the present disclosure. As compared with the semiconductor device 100C in FIG. 25 , the semiconductor device 100D further comprising a first protruding portion extending from a lower portion of the first metal spacer 701 and toward to the air gap 700A, and the second metal spacer 703 is positioned on the first protruding portion. In some embodiments, a combined width of the first protruding portion and the air gap is equal to or greater than a top width of the plug 503.

Due to the design of the semiconductor device of the present disclosure, the plurality of metal spacers may decrease the seams and voids when filled high aspect ratio electroplated metal structure of the semiconductor device, therefore, the electrical transport performance of the semiconductor device may be improved.

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. For example, many of the processes discussed above can be implemented in different methodologies and replaced by other processes, or a combination thereof.

In some embodiments, an integrated circuit disposed on a semiconductor substrate is divided into different regions, and the regions have different pattern densities per unit area. For example, a memory circuit may have a dense region for memory cells and a loose region for peripheral elements, such as row or column decoder. Reference is made to FIG. 27 and FIG. 27 . FIG. 27 is a schematic diagram of an integrated circuit form a top view according to some embodiments of the present disclosure. FIG. 28 is a schematic diagram of a semiconductor device 200 according to some embodiments of the present disclosure. The integrated circuit is disposed on a substrate and includes a dense region DR and a loose region LR. The semiconductor device 200 is implemented in the dense region DR. In some embodiments, the semiconductor devices 100A, 100B, 100C, and 100D mentioned above may be implemented in the loose region LR.

As illustrate in FIG. 27 , a semiconductor device 200 is disposed in the dense region DR and one of the semiconductor devices 100A, 100B, 100C, and 100D is disposed in the loose region LR.

The semiconductor device 200 is similar to the semiconductor devices 100A, 100B, 100C, and 100D. The semiconductor device 200 includes a substrate 101, a first insulating film 901, a second insulting film 903, a third insulating film 905, and a sealing film 907 sequentially disposed.

A plurality of isolation structures 103 are disposed in the substrate 101 and configured to define an active area 105. A first doped region 107 is disposed in an upper portion of the active area 105.

A plurality of second doped regions 301 and a poly line 200 are disposed in the first insulating film 901. The second doped regions 301 are in contact with the first doped region 107, and the poly line 200 us disposed between the second doped regions 301. In some embodiments, the second doped regions 301 are formed by performing an epitaxial process.

A plurality of contacts 403, a first plug 501, and a plurality of second plugs 503 are disposed in the second insulting film 903. The first plug 501 is electrically coupled to the poly line 200 through the one of the contact 403, and the second plugs 503 are electrically coupled to the second doped regions 301 through the contact 403. As illustrated in FIG. 28 , the contacts 403 are in contact with the second doped regions 301 and the poly line 200, in which the contacts 403 are separated from each other. The poly line 200 is the same as the poly line shown in FIG. 1 , which includes a gate oxide 203, a poly gate 207, and spacers 211

A plurality of metal spacers 601, a plurality of metal spacers 603, and a plurality of air gaps 600 are disposed in the third insulating film 905. The configurations of the metal spacers 601, the metal spacers 603, and the air gaps 600 are the same as these elements shown in FIG. 1 , therefore, the details are not repeated herein. In other embodiments, the configurations of the metal spacers 601, the metal spacers 603, and the air gaps 600 are the same as these elements shown in FIG. 2 .

In some embodiments, the materials and the manufacturing processes of the semiconductor device 200 are similar to the materials and the manufacturing processes of the semiconductor device 100, A, 100B, 100C, and 100D.

In some embodiments, the active area 105 in the dense region DR further includes a narrow portion 105 a as illustrated in FIG. 27 . From the top view, a width W1 of the active area 105 in the dense region DR is substantially equal to a width W1 of the active area 105 in the loose region LR. However, a width W2 of the narrow portion 105 a in the dense region DR is less than a width W3 of a middle portion 105 b of the active area 105 in the loose region LR.

The narrow portion 105 a and the middle portion 105 b are disposed below the respective poly line 200. In some embodiments, the shape of the first doped region 107 has the same shape as the active area 105 form the top view. In other words, in the dense region DR, the portion of the first doped region 107 below the poly line 200 has a smaller width in the direction X than other portion of the first doped region 107 below the second doped regions 301. In some embodiments, the width W3 is equal to the width W1.

An aspect of the present disclosure provides a semiconductor device including a substrate, an active area in the substrate, a first plug positioned above the active area, second plugs positioned above the active area, metal spacers positioned above the first plug and the plurality of second plugs, and air gaps respectively positioned between the plurality of metal spacers. The active area comprises a narrow portion having a first width and two side portions having a second width, wherein the narrow portion is disposed between the two side portions, and the first width is less than the second width from a top view.

Another aspect of the present disclosure provides a method for fabricating a semiconductor device. The method includes: providing a substrate; forming an active area in the substrate; forming a first plug above the active area; forming a plurality of second plugs above active area; forming a plurality of metal spacers above the first plug and the plurality of second plugs; and forming a plurality of air gaps positioned between the plurality of metal spacers. The active area comprises a narrow portion having a first width and two side portions having a second width, wherein the narrow portion is disposed between the two side portions, and the first width is less than the second width from a top view.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, and steps. 

What is claimed is:
 1. A semiconductor device, comprising: a substrate; an active area in the substrate, wherein the active area comprises a narrow portion having a first width and two side portions having a second width, wherein the narrow portion is disposed between the two side portions, and the first width is less than the second width from a top view; a first plug positioned above the active area; a plurality of second plugs positioned above the active area; a plurality of metal spacers positioned above the first plug and the plurality of second plugs; and a plurality of air gaps respectively positioned between the plurality of metal spacers.
 2. The semiconductor device of claim 1, further comprising: a first doped region in the active area; a first insulating film above the substrate and in contact with the first doped region; a second insulating film above the first insulating film; and a third insulating film above the second insulating film.
 3. The semiconductor device of claim 2, further comprising: a plurality of second doped regions disposed in the first insulating film; and a poly line disposed in the first insulating film, wherein the poly line is disposed between the plurality of second doped regions.
 4. The semiconductor device of claim 3, wherein the poly line is disposed over the narrow portion from the top view.
 5. The semiconductor device of claim 3, wherein the first plug and the plurality of second plugs are disposed in the second insulating film, and the first plug is electrically coupled to the poly line through a first contact, and the plurality of second plugs are electrically coupled to the plurality of second doped regions through a plurality of second contacts, respectively.
 6. The semiconductor device of claim 5, wherein the plurality of metal spacers are disposed in the third insulating film, and comprise: a first set of metal spacers; a second set of metal spacers; a third set of metal spacers; and a fourth set of metal spacers, wherein the second set of metal spacers is positioned between the first set of metal spacers and the third set of metal spacers, and the third set of metal spacers is positioned between the second set of metal spacers and the fourth set of metal spacers.
 7. The semiconductor device of claim 6, wherein the first set of metal spacers and the third set of metal spacers are in contact with the plurality of second plugs, respectively.
 8. The semiconductor device of claim 6, wherein the second set of metal spacers is in contact with the first plug.
 9. The semiconductor device of claim 6, wherein the fourth set of metal spacers is in contact with the second insulating film.
 10. The semiconductor device of claim 6, wherein the first set of metal spacers comprises: a first metal spacer having a first sidewall and a second sidewall, wherein the first sidewall is perpendicular to a top surface of the second insulating film; and a second metal spacer attached to the second sidewall of the first metal spacer.
 11. The semiconductor device of claim 10, wherein a bottom width of the first set of metal spacers is equal to a top width of one of the plurality of second plugs.
 12. The semiconductor device of claim 10, wherein a bottom width of the first set of metal spacers is greater than a top width of one of the plurality of second plugs.
 13. The semiconductor device of claim 10, wherein the first set of metal spacers and the second set of metal spacers are mirror symmetry.
 14. The semiconductor device of claim 10, wherein the first set of metal spacers further comprises: a first protruding portion extending from a lower portion of the first metal spacer and toward to the second set of metal spacers.
 15. The semiconductor device of claim 14, wherein a width of the first protruding portion is equal to a top width of the one of the plurality of second plugs.
 16. The semiconductor device of claim 14, wherein a width of the first protruding portion is greater than a top width of the one of the plurality of second plugs.
 17. The semiconductor device of claim 14, wherein the second metal spacer is positioned on the first protruding portion.
 18. The semiconductor device of claim 6, wherein the fourth set of metal spacers is a dummy structure.
 19. The semiconductor device of claim 6, wherein the third set of metal spacers comprises: a third metal spacer positioned having a third sidewall and a fourth sidewall, wherein the third sidewall is perpendicular to a top surface of the second insulating film; and a fourth metal spacer attached to the fourth sidewall of the third metal spacer. 